pcmhacking.net

Hello All,
I have installed GM EFI on a MG Midget engine. I have driven the car about 100 miles on 12P and have data logged and made live changes using the Moats AutoProm. I am very impressed with how well it all works and how much info you all have shared.
Before going any further with this I have a few question if you don't care if I ask.
First let me give you a few details.
Engine size 91ci or 1500cc
Bore 2.90 Stroke 3.44
GM distributor and alternator fitted to the MG engine.
1227165 ECM with all GM sensors except there is no Knock sensor
20 PSI fuel pressure with external pump and regulator.
A single TBI 58 Lbs Hr injector.
Manual transmission.

Now the questions.
What 12P code would you recommend I start with?
How critical is the injector flow rate setting. I found the need to raise it by .05 from what I calculated with the Kinjflow calculator because it was very lean. Is this a sign of some type of problem?
Should the RPM Derivative Spark Control be used?
Any other suggestions are welcome.

Thanks

POZE wrote:What 12P code would you recommend I start with?

Can try the 4 cyl Isuzu bin $12P-V111-IsuzuG200W and see if that runs better as starting point .. https://pcmhacking.net/forums/viewtopic.php?f=7&t=375
But with the engine running your a step ahead already so I would just develop what you have now. As there is no cal posted on here to suit your engine you will have to adjust a fair bit with whatever cal you start with.

POZE wrote:How critical is the injector flow rate setting. I found the need to raise it by .05 from what I calculated with the Kinjflow calculator because it was very lean. Is this a sign of some type of problem?

Set kinjflow to match the injectors, maybe a touch more and start tuning the VE table - if you get to 100% VE then you may need to adjust kinjflow. You dont want to initially fudge kinjflow to make an incorrect VE table run right.

POZE wrote:Should the RPM Derivative Spark Control be used?

Id turn it off to start with. When everything is setup enable it and have a play with the settings. If your not sure what it is there is some info in the FAQ .. https://pcmhacking.net/forums/viewtopic.php?f=7&t=1396

Where should the IAT sensor be installed for the 12P code? I have it in the fresh air inlet for the air cleaner. I have also seen them installed in the intake manifold runners?
Thanks

in map sensor based cars, they are in an intake runner. worst comes to worse, put it in the plenum. definitely not the airbox.

Jayme wrote:in map sensor based cars, they are in an intake runner. worst comes to worse, put it in the plenum. definitely not the airbox.

haha thats were they put the IAT sensor on my stato someone put a vsIII engine in it and was lazy to take the manifold out of and drill it so they just got a later model air filter box top and used the sensor hole in that. havent gotten around to changing it yet

Thanks Jayme. Drilled the intake today and put the IAT in an intake runner. Defiantly changed the way the engine runs. Can't wait to drive it and see how it acts.

Have a lean spike created by a quick throttle opening. Tried to remove spike with the AE Multiplier Vs Engine RPM Table and AE Temperature Factor Vs Coolant Temp. The AE Temp Factor Vs Coolant Temp adjustment helped but makes the AFR go rich after the spike. What am I missing?
Thanks

is there any lean spots in the VE table that your passing through which might cause it ....

is it always at similar rpms ? if so try a higher stab and see if it doesn't do it etc ?

Thanks Holden.....I see the lean spike at different RPM's.
Would anyone like to share a data log from a well tuned engine? Just want to observe the data monitor activity.
Thanks

i haven't got any logs on hand, but i have a screen shot from some racing on saturday.



now i wouldn't say this is a perfect tune, but you can see, in the bottom monitor target afr (TAF) is in dark blue and wideband (AWB) is in green, and it is mostly following the target, and the good thing about this log is there is alot of on and off the throttle (TPS in top monitor) which shows the wideband going lean as the throttle comes off and richens back up as the throttle is applied again.